【作者】 刘丹；

【导师】 戚向东； 谢朝晖；

【作者基本信息】 燕山大学 ， 工程硕士（专业学位）， 2018， 硕士

【摘要】 针对窄带优钢冷轧后表面起皮现象,通过对起皮的相关检测分析表明,起皮处发现大量铁和还原铁,是造成冷轧起皮的直接起因,而铸坯在加热炉内形成的微裂纹是造成起皮的根本原因。结合50,65Mn等优钢特点,分析了铸坯在加热炉内组织转变的规律,研究了不同条件下中间坯质量情况。结果表明,铸坯在630-700℃入炉时,钢种的相变温度Ac1正好处于此温度区间,由于加热炉的结构特点,铸坯在加热炉预热段经历了长时间相变,造成珠光体、铁素体和奥氏体的共存,从而引起较大的组织应力,导致铸坯内部微裂纹的产生,随着微裂纹的扩展,铸坯的氧化也逐步深入,并在裂纹内部充满了氧化铁,同时形成严重脱碳。而热轧工序无法及时清除此氧化铁,引起热轧带钢表面质量缺陷,后续随着冷轧的变形深入,此氧化铁逐渐暴露出来,并在冷轧带钢表面形成起皮。基于现场工况条件与设备实际情况,重新优化了生产组织模式,根据钢种和用途优化了中包温度,连铸实行恒拉速控制,拉速最大波动范围±0.05m/min,优化铸坯入炉温度,特殊用途优钢用冷坯生产,杜绝铸坯微裂纹的出现,遏制铸坯内部氧化。经过跟踪客户使用情况,冷轧后表面起皮得到显著改善,不仅获得客户新的认可,还提高了质量和品牌效应,为下一步优钢向高端迈进奠定了基础。更多还原

【Abstract】 Through analysis of the peeling after cold rolling of narrow strip special steel,we discovered mass reduction iron.This is the fundamental cause of cold rolling peeling,and the immediate cause is the micro-cracks of billets in furnace.Base on characteristics include 50 、 65 Mn etc,we have analyzed phase transformation characteristic of billet in furnace,and have researched intermediate billet qualities with different conditions also.The results indicated that the Ac1 temperature of special steel is in range of billets hot charging temperature,as a result of furnace structure characteristic,there is a long time phase change of billets in preheating zone.Then pearlite、ferrite and austenite had co-existence,so structural stress appeared and microcracks formed interior billets.The billets oxidized deeply with micro-cracks expanding,the same time scale was full of internal of cracks and decarburization was forming.But hot rolled can not get rid of the scale completely,the scale would expose and peel with cold rolled deeply.Base on field condition and facilities,we have optimized pattern of production、charging temperature、tundish temperature、constant pulling rate of casting with the range of ±0.05m/s,meanwhile we product steel according to special use in cold billets to keep from micro-cracks and stop internal oxidation of billets.The surface peeling has been significantly improved in cold rolled through market tracking.Not only got the accepts of customers,but also improved quality and brand effect,meanwhile,we will lay foundation towards high-end special steel.更多还原